The BBC director general, George Entwistle, has promised to investigate the mounting allegations of sexual abuse by Sir Jimmy Savile, but only when the police investigation has been completed.

Entwistle told BBC Radio 4's Today programme on Monday that he deeply regretted what had happened and apologised to the women involved for what they have had to endure, but he said he did not want to compromise the police inquiry.

"I think this has to be done in two phases," Entwistle said. "First the police are given the chance to do everything they have to do – that is the only way justice can possibly be done for the women in question. But once the police assure me that they have done everything they have to do, then, we can take a look properly."

Entwistle said the police are also looking at the people who worked with Savile and examining whether criminal charges will be brought against them.

"The police have made clear to me is that other people around Jimmy Savile may have known things that should have and would have properly been a matter of criminal inquiry. I can't prejudge that," Entwistle said.

Entwistle, who rose through the ranks of the BBC as a journalist, said he had not about heard the rumours of sex abuse until late last year but conceded: "Jimmy Savile was regarded as by a great many people as odd, a bit peculiar and that was something I was aware some people believed."

He also revealed that he was told last December that Newsnight had launched an investigation – which was later dropped – into allegations of sexual abuse against Savile. The programme's reporters spoke to 10 women who claimed they had been abused or had knowledge of abuse at the Duncroft school at the height of his fame in the 1970s.

Entwistle insisted that the Newsnight editor Peter Rippon was not pressurised to drop the film, and its shelving had nothing to do with tribute programmes that were scheduled in the wake of Savile's death last October.

"I didn't know what had become of that investigation," Entwistle said. "I didn't know of discoveries, if any, that they had made. A great many people in the country loved Jimmy Savile and wanted to contribute to that programme."

On Sunday, former director general Mark Thompson said he had "no involvement whatsoever not to pursue the Newsnight investigation".

"I never heard of any rumours nor received any complaints or allegations [about Jimmy Savile] while I was director general at the BBC," said Thompson.

Entwistle described the last week's revelations as "awful". "The women involved here have gone through something awful and something I deeply regret that they should have to go through and I would like to apologise on behalf of the organisation to each and every one of them for what they've had to endure here," he said.

"When the police have finished everything they have to do and when they give me an assurance there is no danger of us in any way compromising or contaminating an investigation. I will take it further and make sure that any outstanding questions are answered properly.

"We need a comprehensive examination of what went on here but at the heart of what went on here are a series of criminal allegations about the behaviour of Sir Jimmy Savile.

"The way to deal with those is to make sure that the police, who are the only properly constituted authority for dealing with investigations are allowed to make the examinations and inquiries they need to make."

Entwistle added that he spoke to two senior police officers last week and told them they would have the full support of the BBC investigations unit.

"It really is important that the police are given the chance to do that here – the BBC does not have the capacity to compel people who no longer work for it, to give interviews. It does not have the capacity to secure evidence forensically. It is vital – and the police asked me specifically on this point – to make sure that we do nothing to compromise a criminal examination of events," he said.

The corporation has come under heavy pressure to hold its own inquiry into the wider allegations that sexual abuse and harassment were routine and was tolerated in both radio and TV in the 1970s and 1980s.

Writing in Monday's Daily Mail, Janet Street-Porter reveals how when she started work at BBC in the late 1980s it was a "bastion of male chauvinism". She said: "The general attitude in Light Entertainment was 'sexual harassment – bring it on!'."

Since ITV's investigation into Savile was aired last week, more than a dozen women have come forward to claim they were abused by the star at the BBC, in his Rolls-Royce or in his camper van and by others working at the corporation.

Former Radio 1 DJ Liz Kershaw, revealed at the weekend that she had been routinely groped while working at the station, where Savile also made his name, and said her protests were dismissed by her bosses.

"I couldn't say anything. I couldn't even exclaim because I was broadcasting to the nation. And when I complained to somebody, they were incredulous, and said 'What? Don't you like it? Are you a lesbian?'," she said.

Sandi Toksvig, the television and radio presenter, disclosed that she had once been molested while on air earlier in her career by a "famous broadcaster". She said that when she complained it was been simply laughed off.

On Sunday, David Cameron called for the BBC to hold a full internal investigation into the "truly shocking" allegations.

• To contact the MediaGuardian news desk email editor@mediatheguardian.com or phone 020 3353 3857. For all other inquiries please call the main Guardian switchboard on 020 3353 2000. If you are writing a comment for publication, please mark clearly "for publication".

• To get the latest media news to your desktop or mobile, follow MediaGuardian on Twitter and Facebook